Photoelectric sound reproduction of phonograms



F. CRUDO Dec. 22, 1936.

PHOTOELEGTRIG SOUND REPRODUCTION OF PHONOGRAMS 2 Sheets-Sheet 1 Filed Dec. 13, 1954 Invenfir: I'ermdb Oraolo,

Dec. 22, 1936. F. CRUDO PHOTOELECTRIC SOUND REPRODUCTION OF PHONOGRAMS Filed Dec. 13, 1934 2 Sheets-Sheet 2 menzor: Rrnando Crude,

Patented Dec. 22, 1936 UNlTED STATES PATENT OFFlQE PHOTOELECTRIC SOUND REPRODUCTION OF PHONOGRAMS Application December 13, 1934, Serial No. 757,409 In Germany April 14, 1934 11 Claims.

The present invention relates to a process for improving the photoelectric sound reproduction of phonograms having discontinuous sound tracks, and is characterized by the fact that it suppresses detrimental effects in the sound re-- production thereof to such extent that said discontinuity is imperceptible to the ear.

Accordingly, my invention is particularly important in the case of phonograms of rectangular or similar shape, which are applied on cylindrical phonogram carriers and which of necessity must have discontinuous sound tracks. When the overlapping edge of these phonograms, assuming the latter to be folded about their car- 3 riers, passes in front of the pencil of light of a photoelectric collector, thereby reflecting the light to a photoelectric cell, a sudden variation takes place in the light which reaches said cell, this variation causing an intense pulsation of electric current, which ordinarily gives rise to a disturbing noise in the loudspeaker, and which noise is reproduced with each revolution of the cylinder or carrier.

The present invention provides means which at each time the said joining edge approaches the pencil of light, momentarily intercepts the light, either partially or completely, at any desired point between the light focus and the one or more photoelectric cells. Of course if desired,

said means may also be designed to act in a somewhat similar manner on the electric circuit which has been completed by the energization of the photoelectric cell. The term photoelectric cell is of course intended to indicate any lamp or device which translates light variations into electric variations.

The correct operations of the various means employed is ensured by properly synchronizing their operation with the revolutions of the phono- 40 gram carrying cylinder, or in brief, with the passage of the joining edge of the phonogram in front of the pencil of light of the photoelectric collector.

Whatever form the means employed may take,

45 their design is such that they will produce a partial or total interruption either of the light reaching the photoelectric cell, or of the electric current generated therefrom; and this interruption will preferably be effected smoothly and 00 gradually, in order to substitute the sudden dissonant noise caused by the phonogram joining end by a practically inaudible low frequency wave.

If desired, the shutter device which I will describe hereinafter may also serve for fixing the 55 phonogram on the carrier or cylinder,

The process of the present invention may be carried out in different manners, as is evident from the following:

(a) The partial or total interruption of the light pencil may be caused by influencing the energization of the source of light itself, ecreasing the energization thereof periodically and synchronously with the rotation of the cylinder.

(1)) The interruption may also be effected by means of a shutter which, at a particular point 10 of each revolution of the cylinder or carrier, either wholly or partially interrupts the pencil of light in a plane in the path between the light source and the phonogram.

(c) The interruption may also be effected, dur- 16 ing each rotation of the cylinder, either by tracing on the edges of the phonogram a wave in each track of such pitch that it is inaudible to the ear; or by applying a holding device applied on the phonogram edges, which device causes 20 smooth variations in the reflected light beam.

(d) The interruption may also be effected synchronously with the revolutions of the cylinder by means of a shutter which periodically cuts the pencil of light reflected from the phonogram to the photoelectric cell.

(c) The interruption may also be effected by breaking the electric circuit controlled by the photoelectric cell, regardless of whether this current has been amplified, which interruptions take place periodically and should act synchronously with the revolutions of the cylinder.

The synchronization of the interrupting means with the cylinder may be obtained by mechanical or electromagnetic means, which if desired, may act at a distance from the phonogram.

In order that the invention may be more clearly understood, reference is made by way of example to the several preferred embodiments illustrated in the accompanying drawings, wherein the same reference characters indicate like or corresponding parts or elements.

Therein, Fig. 1 is a front view of a carrier on which is mounted a phonogram of the type which I employ;

Figs. 2 and 3 are fragmentary transverse sec tions showing different manners of joining the ends of the phonogram on the carrier;

Figs, 4-6 inclusive show different types of waves 5 which can be drawn on the ends of the sound tracks on the phonograms;

Fig. '7 shows schematically and in plan the main parts of an electro-magnetic shutter according to my invention, while Fig. 8 is a view at right angles to Fig. 7, showing certain additional points;

Fig. 9 is a schematic end view showing the carrier and its circuit connections with the photoelectric cell;

Fig. depicts schematically a second manner or interrupting the sound reproduction;

Fig. 11 is an elevation and Fig. 12 an end view, of a modified carrier; while Figs, 13, 15, l7, l9, and 21 are showings of details, Figs. 14, 16, 18, and 22 are corresponding sections therethrough, respectively.

In Figure 1 the phonogram l is shown as applied on a cylindrical phonogram carrier 2, the manner being shown in which the sound tracks end in order to obtain inaudible, gradual waves capable of nullifying the noise resulting from the abrupt joint between the edges of the phonogram. The edges 3 of the phonogram may be joined in abutting relation, as in Fig. 2, or in overlapping manner, as in Fig. 3, either of which two methods are detrimental per se, and the disadvantageous effect of which is remedied by my invention.

As suggested previously, the undesirable noise may be suppressed by providing an inaudiblewave at the end of each sound track of the phonogram 1.

One such wave Q is shown in Fig. 4:, and this wave may be black or any other suitable color, this color preferably being also given to the edges of the phonogram;

While another type or" inaudible wave 5 is shown in Fig. 5; still Another type of wave 6 being shown in Fig. 6. This last wave provides zones of increasing darkness in each sound track.

Referring now to Figs. '7 and 8, the electromagnetic shutter is constituted by a plate I of opaque material having a transverse slot 8. It also serves as a support for the coil 9 of an electromagnet, as well as for the bracket H), which carries a biasing screw H. The bracket piece i2 is also mounted on the plate I, this bracket carrying the flexible sheet 53 or armature, which latter is turned at one end to form the shutter M. A battery i5 and an electric current switch l6 are series connected with the coil 8, armature l3, screw H, and bracket ii).

As shown in Figure 8 the shutter of Fig. 7 is associated with the phonogram l and with the photoelectric collector ll, the latter comprising a light source l8 projecting a light beam through the lens system 9 to concentrate the pencil of light on the phonegram. The light beam is adapted to be interrupted periodically by the shutter Hi. The photoelectric cell 20 picks up the light reflected from the phonogram.

Reference to Figure 9 will show in somewhat greater detail the relation between the cylindrical phonogram carrier and the photoelectric collector ii. The cylinder 2 is shown as being provided with a stop 2i which actuates the flexible armature 22 of an interrupter 23 at each revolution of the cylinder.

In Figure 10 the output circuit of the photoelectric cell 23 is interrupted in order to suppress dissonance resulting from the joint of the phonegram. The transformer 24, and battery are in circuit with the cell, while the condenser 26 and resistance comprising a grid leak, are adapted to be connected to the grid of the amplifier 28, and to be shunted when desired by the interrupter 29. Since they form no part of this invention neither the remainder of the amplifier circuit or the loudspeaker have been illustrated.

In Figure 11 the cylindrical phonogram carrier 2 is provided with a rod fixed thereon by arms 3! pivoted to studs or axles 32. The rod 30 is pulled against the edges of the phonogram l, by a spring or the like and since it is of suitable color, it will produce a smooth inaudible variation of light on each revolution of the cylinder; while at the same time, the rod 30 fixes the phonogram l in position.

The correct position of the phonogram longitudinally on the carrier 2 is ensured by the guide stops 337 In Figures 13 and 14 is shown screw threaded rod portion which, due to the degree of obliqueness of its thread, produces gradual and inaudible variations of light when it is passed in front of the photoelectric collector. This rod, which may be substituted for the rod 30 of Fig. 11, is likewise located on the joining edge of the phonogram, and thus avoids the detrimental sound eiIect caused by the said edge.

In Figures 15 and 16 a helicoidal spring 35 is substituted for the rod 33 of Fig. 11 and the rod 35 of Fig. 13 and is applied on the joining edges of the phonogram 1. Due to the degree of obliqueness of its turns, the spring nullifies the detrimental noise-producing effect of the joining edge.

In Figures 17 and 18 is a further means for joining the edges of the phonogram, in the form ing device in the shape of small teeth 38 applied on the edges of the phonogram l. The teeth 38 are integral with the rods 39, which are joined to the cylinder 2 by suitable means such as arms 48 and axles M. The springs 42 urge the teeth 38 outwardly towards the surface of the cylinder 2. Every time these teeth pass in iront of the photoelectric collector, they cause smooth variations of light.

In Figures 21 and 22 is shown a translucent rod 43, of prismatic shape, applied on the edges of the phonogram I. Inasmuch as the edges of this red transmit light much more readily than does the thicker center portion, the rod produces smooth variations of light during its passage in front of the photoelectric collector.

To summarize briefly, the phonograin l, applied on the cylindrical phonograzn ca rier 2, forms along the joining edges 3 thereof transverse line which produces a detrimental sound effect during the sound reproduction, as can be understood from Figure 1. This undesirable effect is avoided, for example, by causing the gradual variation of light at such times as the edge 3 passes in front of the photoelectric collector IT or, as already stated, by impressing a similar change on the output circuit of the photoelectric cell 20.

The operation of the electromagnetic shutter shown in Figures 7, 8 and 9 is effected as follows:

The cylinder 2, on each revolution thereof, produces by means of the stop 2! the closing of the electric circuit of the battery 15 through an interrupter it or 23. The interruption coincides exactly with the passage of th joining edge 3 of the phonograin in front of the sncil of light of the photoelectric collector ll.

Every time the interrupter 16 or 23 is closed, the circuit of the battery l5 remaining closed by means of the iron core coil 9, armature l3, screw II and angular bracket [0, the attraction of the armature l3 by the electromagnet is brought about, and it simultaneously closes the slot 8. This closing of the slot 8 takes place gradually due to the oblique nature of one of the edges of the shutter l4. Since it is the slot 8 which permits the passage of the light originated in the light source l8 and which is later concentrated on the phonogram I, the effect thus obtained is that of a smooth decrease and later a smooth increase of the light illuminating the phonograms, said light then being reflected to the photoelectric cell 20.

The operation of the device shown in Figure 10 is as follows:

The synchronization of the breaking of the output circuit of the photoelectric cell with the revolutions of the cylinder is obtained in the same manner as with the device previously explained, the interrupter T28 acting in such manner that when it is closed the sudden variations of electric current resulting from the sudden change of light reaching the photoelectric cell when the edge of the phonogram 3 passes in front thereof, do not reach the valve 28, inasmuch as the resistance 2'! and condenser are shunted, so that the grid of the valve 28 is cut out of circuit.

The edge-joining devices illustrated in Figures H and 22 cover the joining edges of the phonogram in such manner as to produce smooth or soft variations of light each time they pass in front of the photoelectric collector.

It should be understood that in carrying the invention into practice, many structural modifications are possible without departing from the scope of the present invention.

For example, it is possible for the shutter illustrated in Figures 7 and 8, instead of being opaque, to be translucent, or of suitably colored or uncolored translucent or transparent material, and disposed at the most suitable places. Likewise the electric interrupter may be located at any part of the output circuit of the photoelectric cell and may be varied as regards its constructional details.

What is claimed is:-

1. Apparatus for improving the photoelectric sound reproduction oi. a device including rotary cylindrical phonogram carriers for sheet-shaped phonograms, comprising a source of light, means for directing light rays from said source of light, an electrical pick-up including at least one photoelectric cell for receiving the rays reflected from the phonograms and for converting the rays 'into sound energy, said last-mentioned means including a sound-distributing device,

means synchronized with the revolutions of the phonogram carriers and adapted to at least partially interrupt momentarily the transmission of energy to the sound distributing device each time the light rays scan the joints formed between adjacent ends of the phonograms, and a screwthreaded rod applied over and joining together ends of each phonogram, capable of producing smooth and continuous variations of light each time it is scanned by the light rays.

2. Apparatus for improving the photoelectric sound reproduction of a device including rotary cylindrical phonogram carriers for sheet-shaped phonograms, comprising a source of light, means for directing light rays from said source of light, an electrical pick-up including at least one photoelectric cell for receiving the rays reflected from the phonograms and for converting the rays into sound energy, said last-mentioned means including a sound-distributing device, means synchronized with the revolutions of the phonogram carriers and adapted to at least partially interrupt momentarily the transmission of energy to the sound distributing device each time the light rays scan the joints formed between adjacent ends of the phonograms, and a helicoidal spring ap plied over and joining together the adjacent ends of each phonogram, capable of producing smooth and continuous variations of light each time it is scanned by the light rays.

3. Apparatus for improving the photoelectric sound reproduction of a device including rotary cylindrical phonogram carriers for sheet-shaped phonograms, comprising a source of light, means for directing light rays from said source of light, an electrical pick-up including at least one photoelectric cell for receiving the rays reflected from the phonograms and for converting the rays into sound energy, said last-mentioned means including a sound-distributing device, means synchronized with the revolutions of the phonogram carriers and adapted to at least partially interrupt momentarily the transmission of energy to the sound distributing device each time the light rays scan the joints formed between adjacent ends of the phonograms, and teeth or hooks applied over and joining together with adjacent ends of each phonogram, capable of producing smooth and continuous variations of light each time it is scanned by the light rays.

4. Apparatus for improving the photoelectric sound reproduction of a device including rotary 1 cylindrical phonogram carriers for sheet-shaped phonograms, comprising a source of light, means for directing light rays from said source of light, an electrical pick-up including at least one photoelectric cell for receiving the rays reflected from the phonograms and for converting the rays into sound energy, said last-mentioned means including a sound-distributing device, means synchronized with the revolutions of the phonogram carriers and adapted to at least partially interrupt momentarily the transmission of energy to the sound distributing device each time the light rays scan the joints formed between adjacent ends of the phonograms, and a rod of translucent or transparent material applied over and joining together the adjacent ends of each phonogram, capable of producing smooth and continuous variations of light each time it is scanned by the light rays.

5. Apparatus for improving the photoelectric sound reproduction of a device including rotary cylindrical phonogram carriers for sheet-shaped phonograms, comprising a source of light, means for directing light rays from said source of light, an electrical pick-up including at least one photoelectric cell for receiving the rays reflected from the phonograms and for converting the rays into sound energy, said last-mentioned means including a sound-distributing device, and means synchronized with the revolutions of the phonogram carriers and adapted to at least partially interrupt momentarily the transmission of energy to the sound distributing device each time the light rays scan the joints formed between adjacent ends of the phonograms, low-frequency sound waves being traced on the joining ends of each phonogram, to render less abrupt any dissonance resulting from the passage of this joint past the scanning light rays.

6. Apparatus for improving the photoelectric sound reproduction of a device including rotary cylindrical phonogram carriers for sheet-shaped phonograms, comprising a source of light, means for directing light rays from said source of light, an electrical pick-up including at least one photoelectric cell for receiving the rays reflected from the phonograms and for converting the rays into sound energy, said last-mentioned means including a sound-distributing device, and means synchronized with the revolutions of the phonogram carriers and adapted to at least partially interrupt momentarily the transmission of energy to the sound distributing device each time the light rays scan the joints formed between adjacent ends of the phonograms, low-frequency sound waves being traced on the joining ends of each phonogram, to render less abrupt any dissonance resulting from the passage of this joint past the scanning light rays, said low-frequency waves occupying less than the entire width of the tracks.

'7. Apparatus for improving the photoelectric sound reproduction or" a device including rotary cylindrical phonogram carriers for sheet-shaped phonograms, comprising a source of light, means for directing light rays from said source of light, an electrical pick-up including at least one photoelectric cell for receiving the rays reflected from the phonograrns and for converting the rays into sound energy, said last-mentioned means including a sound distributing device, and means which, in accordance with the rotations oi the cylinder and at regular intervals, momentarily interrupt, at least partially, the transmission of energy to the sound distributing device each time the light rays scan the joints formed between adjacent ends of the phonograms, and a bar applied on the edges forming the joint of the phonogram, for holding the same in place.

8. Apparatus for improving the photoelectric sound reproduction of a device including rotary cylindrical phonogram carriers for sheet-shaped phonograms, comprising a source of light, means for directing light rays from said source of light, an electrical pick-up including at least one photoelectric cell for receiving the rays reflected from the phonograms and for converting the rays into sound energy, said last-mentioned means including a sound distributing device, and means which, in accordance with the rotations of the cylinder and at regular intervals, momentarily interrupt, at least partially the transmission of energy to the sound distributing device each time the light rays scan the joints formed between adjacent ends of the phonograms, said interrupting means being constituted by means applied over and joining together the ends of each phonogram, whereby the interrupting means is capable of producing smooth variations of light each time the joint is scanned by the light rays.

9. Apparatus for improving the photoelectric sound reproduction of a device including rotary cylindrical phonogram carriers for sheet-shaped phonograms, comprising a source of light, means for directing light rays from said source of light, an electrical pick-up including at least one photoelectric cell for receiving the rays reflected from the phonograms and for converting the rays into sound energy, said last-mentioned means including a sound distributing device, and means which, in accordance with the rotations of the cylinder and at regular intervals, momentarily interrupt, at least partially the transmission of energy to the sound distributing device each time the light rays scan the joints formed between adjacent ends of the phonograms, said interrupting means being constituted by a rod applied over and joining together the ends of each phonogra-m, capable of producing smooth variations of light each time the joint is scanned by the light rays.

10. Apparatus for improving the photoelectric sound reproduction of a device including rotary cylindrical phonogram carriers for sheet-shaped phonograms, comprising a source of light, means for directing light rays from said source of light, an electrical pick-up including at least one photoelectric cell for receiving the rays reflected from the phonograms and for converting the rays into sound energy, said last-mentioned means including a sound distributing device, and means controlled by the rotations of the cylinder which at regular intervals, momentarily interrupt, at least partially, the transmission of energy to the sound distributing device each time the light rays scan the joints formed between adjacent ends of the phonograms.

11. Apparatus for improving the photoelectric soiuid reproduction of a device including rotary cylindrical phonogram carriers for sheet-shaped phonograms, comprising a source of light, means for directing light rays from said source of light, an electrical pick-up including at least one photoelectric cell for receiving the rays reflected from the phonograms and for converting the rays into sound energy, said last-mentioned means including a sound distributing device, and means fixed to the cylinder which, at regular intervals, put in operation the means which momentarily interrupt, at least partially, the transmission of energy to the sound distributing device each time the light rays scan the joints formed between adjacent ends of the phonograms.

FERNANDO CRUDO. 

